The best open source alternative to Pentaho is Talend. If that doesn't suit you, our users have ranked more than 100 alternatives to Pentaho and 17 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Pentaho are LinceBI (Free, Open Source), EDA (Paid, Open Source), ReportServer (Free, Open Source) and ART Reporting (Free, Open Source).
Talend leverages the open source model to make data integration available to all types of organizations, regardless of their size, level of expertise or budgetary constraints. Talend’s solutions connect to all source and target systems and they can be downloaded at no cost.
The most complete OpenSource Bussines Intelligence platform including BI Portal, Reports, OLAP Analysis, Dashboards and Scorecards
It´s fully customizable and you can include other BI tools in LinceBI BI Global Portal like PowerBI, Metabase.
ReportServer is a web-based business intelligence platform that offers everything you need to evaluate your business. ReportServer comes with powerful ad-hoc analysis tools as well as with support for OLAP and pixel-perfect reporting.
ART is a web based reporting solution. SQL queries can be published in a few minutes. It supports tabular, crosstab, charts, scheduling, email alerts, drill down, among other features. Results are exportable to spreadsheet/pdf.
QueryTree is a flexible and powerful database reporting tool. Simply connect your database and start visualizing your data in minutes. Everything works with a dropdown menu interface - no code or SQL needed.